1. Field of the Invention
The present disclosure relates to an advanced horizontal in-plane switching (AH-IPS) type liquid crystal display device (LCD) and a manufacturing method thereof.
2. Discussion of the Related Art
An LCD displays images using a liquid crystal panel and a backlight unit.
Conventionally, a twisted nematic (TN) type LCD is used. Alternatively, vertical alignment (VA) type and in-plane switching (IPS) type LCDs are widely used.
Recently, an AH-IPS type LCD is developed. The AH-IPS type LCD provides a better viewing angle and contrast ratio than the IPS type LCD.
Figure (FIG. 1 is a cross-sectional view illustrating an AH-IPS type LCD according to related art.
Referring to FIG. 1, the LCD includes an array substrate including a display region OA and a non-display region NA.
In the array substrate, a thin film transistor Tr, a pixel electrode 52 connected to the thin film transistor Tr, and a common electrode 51 are formed on a substrate 10. In the non-display region NA, a gate line (not shown), a data line 20, a gate pad 25 at an end of the gate line, and a data pad 26 at an end of the data line 20 are formed.
The thin film transistor Tr includes a gate electrode 11, a gate insulating layer 12 on the gate electrode 11, an active layer 23 on the gate insulating layer 12, and source and drain electrodes 22 and 21 on the active layer 23. The thin film transistor Tr has an inverted staggered structure. Alternatively, the thin film transistor Tr may have a coplanar structure.
First and second passivation layers 41 and 42 are formed on the thin film transistor Tr. The second passivation layer 42 functions as a planarization layer. When a planarization is not required, the second passivation layer 42 may be omitted.
A common electrode 51 is formed on the second passivation layer 42. A third passivation layer 43 is formed on the common electrode 51 and covers the common electrode 51. A pixel electrode 52 is formed on the third passivation layer 43.
In this configuration, a fringe field is produced between the common electrode 51 and the pixel electrode 52, thus arrangement of liquid crystal molecules is changed by the fringe field.
In the related art LCD, the array substrate for the LCD is manufactured with as many as 6 or 7 mask processes. For example, the array substrate for the LCD is manufactured with one mask process to form the gate electrode 11, one or two mask processes to form the active layer 23 and the source and drain electrodes 22 and 21, one mask process to pattern the first and second passivation layers 41 and 42, one mask process to form the common electrode 51, one mask process to pattern the third passivation layer 43, and one mask process to form the pixel electrode.
Therefore, manufacturing processes of conventional AH-IPS type LCDs are inefficient and manufacturing costs are increased.